This is a demo of the classic Korg VC-10 Vocoder. 

The Korg VC-10 Vocoder came out 1978, together with the Korg MS series synths.

The VC-10 features a full polyphonic keyboard and a dynamic microphone. It has a switchable “ensemble” effect. Vibrato. It also have a (noisy) noise generator for reproducing consonants.

via AnalogAudio1:

The VC-10 sounds quite good. It sounds typically analog. Digital vocoders sound different. Of course the VC-10 is not a Sennheiser or an EMS, but the Korg was also much cheaper. The pitch can also be controlled by an external voltage.

For some reason, the carrier signal is to be heard even without talking in the microphone – almost everytime I press the keys (as you can see in the video). If someone exactly knows the responsible trimpot inside, please let me know.

At the end of the video I played the VC-10 with a delay from Roland DEP-5.

The VC-10 was used by Jean-Michel Jarre, Klaus Schulze, Tomita, Tangerine Dream, Goldfrapp and Air, among others.